Resistor fuse



Patented Aug. 11, 1931` UNITED STATES PATENT OFFICE JOHN K. STAFFORD, F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO OOMPANY, A CORPORATION OF NEW YORK nnsrs'ron rusa Application led Apri1`l2,

Thepresent invention relates to improvements in protective devices Jfor electrical apparatus and especially wherein a resistor element and a fusible element areused to protect` againsty the: destructive action of high-potential high-frequency currents or surges of electricity.

llt has been the common practice heretofore to make the resistor and fuse in two in distinct units, and mount them upon separate supporting means. j

rlhe object of my invention is the production of a combined fuse and resistor element which shall be highly eilicient in operais'tion, 4which shall constitute a single compact structure capable of being handled and installed like any ordinary enclosed fuse, and which may be manufactured at low cost.

For a better understanding ot my invention, attention is directed to the following description and drawing disclosing one embodiment thereof.

The ancompanying drawing shows a sectional view of a resistor fuse embodying my invention.

The fuse member 1 is a standard cartridge or enclosed 'fuse consisting of an enclosing case 2, on the ends of which are secured two 3o ferrules or caps 4, thereby forming an enclosing chamber for a length of proper sized fuse wire 3, which is centrally disposedand securely attached to the ferrules.

Through a hole 5 in the lett-hand tuse as errule 4, the end of a desired length of resistance wire 6 is passed and soldered into place, thereby connecting the resistance wire in series with the fuse wire 3 forming a resistor iuse. The resistance wire is then 4G helically wound toward the right for a portion of its length uponv the fuse casing 2, each turn being in spaced relation with the adjacent turns thereof. The unwound portion of the resistance wire Gis then passed through a hole 7 in a second fibre cylinder or casing 8 of greater length than the enclosed fuse member 1 and which has an inner diameter just suiiicient to permit it to be slid over the cartridge fuse and the wound Wire thereon. The remaining -unwound' re- 1930. Serial No. 443,857.

sistance wire is then wound on the outside of the cylinder 8 and axially in the o posite direction or towards the left end oi tlhe cylinder 8, which acts as an insulation barrier between the two concentric layers of the resistance wire, and the free end threaded through the wall of cylinder 8 and led axially out the end thereof.

A fibre cylinder or casing 9, having an inner diameter just sufficient to pass over the outer coil, is then slid over the whole. Fibre discs 10 are placed at the ends of this outerv cylinder, thereby enclosing the resistor fuse. A terminal wire 11 soldered to the outermost or right-hand ferrule of the cartridge fuse is brought out through the disc 10 and passed through a hole in the terminal end of a cap 12. rlhe cap is-then pushed over the end of cylinder 9 and fastened into place by-screws 13. The lead wire hole is then illed with solder which also securely connects .the lead wire 11 to the cap. The free end of the resistance wire is similarly brought through the opposite disc 10 and the terminal of a cap 14. Cap 14 is then slid over the uncapped end of cylinder 9 and fastened into place by screws 15. The lead wire Ahole in cap 14 is illed with solder securely connecting the terminal lead wire to the cap.

`All spaces within the resistor fuse are lled, prior to the assembly of the insulating l dislr and cap 14 on the cylinder 9 with one of the usual use fillers so that anyv gas formed therein, upon blowing ot the fuse, will be absorbed, thus preventing any arcing from taking place, furthermore it serves to hold the convolutions of the resistance wire in spaced relation and also to promote dissipation of heat.

Thedevice of my improved construction is comparatively simple, can be easily and cheaply manufactured, eliminates a special supporting base formerly necessary for the resistor element, thus cutting down on the housing space, and it also forms an eiicient protection for capacitors, potential trans- Sil formers, and like devices against abnormal and destructive currents coming in over transmission o'r dlstrlbution lines and pre- 2 i Leiaaea vent's abnormal currents from being set up in the protected devices when the fuse blows.

ln accordance with the provisions o the patent statutes, l. have described the prin- 5 ciple of operation of my invention, together with the apparatus which l now consider to represent the best embodiment thereof, but l desire to have it understood that the apparatus shown is only illustrative, and

that the invention may be carried out by other means.

What l claim as new and desire to secure by Letters Patent of the United States, is,-

. l. ln combination, an enclosed fuse, a

i5 bre cylinder radially spaced about said enclosed fuse, a resistance wire connected in series with said fuse and wound partly thereon and partly on said cylinder, an insulating casing tube surrounding said resistance wire, and terminal caps to which said fuse and resistance ends are serially connected and attached to the ends o said casing tube, and a fuse' lling substance packed about all parts therein, whereby any arcing is prevented from taking place within the resistor fuse. n

2. In combination, an enclosed fuse, an outer casing tube of insulating material, an intermediate cylinder of insulating material,

a resistance wireconnected in series with said enclosed fuse and wound `partly thereon passed through the wall of and partly wound on said intermediate cylinder, terminal caps provided with insulating .discs closing the ends of said outer casing, said enclosed use and resistance wire being l serially connected to said terminal caps, and a fuse iller packed about vsaid fuse and resistance wire thereby preventing any arcifng from taking placey Within the resistor use.

3. A' resistor fuse comprising a tubular enclosed fuse, a cylinder of insulating material of substantiall y reater lengthsthan and surrounding sai use in spaced relation, an insulating casing surrounding said cylinder in spaced relation, terminal caps enclosing and attached to the ends of said casin and to one of which the outer end of the fuse is attached, and a resistance wire connected to the inner end of said fuse wound about its enclosure for a part of its length, passed through the wall of the intermediate cylinder and Wound back therein to the terminal cap opposite that to which the fuse is attached, and gas absorbent material illing the spaces between the enclosed fuse and said casing.

lin witness whereof, I have hereunto set my hand this eighth day of April, 1930.

JOHN K. STAFFORD. 

